president obama and mrs. obama left washington this morning, joined on air force one by former president george w. bush and his wife. former presidents clinton and carter also will attend. there's been more unrest in the central african republic, as gunmen refuse to give up their weapons to french troops. the french patrolled the capital city today, trying to disarm rival muslim and christian fighters who killed 400 people over the weekend. we'll have a report from the c.a.r. later in the program. the prime minister of thailand called for new elections today, in the face of protests against her rule. the opposition has accused her of corruption, insisting again she must go. john sparks of "independent television news" reports from bangkok. >> reporter: protest leaders called it the day of reckoning. a time to do-or-die. when their call was answered on the streets of bangkok by more than 150,000 people. and each one seemed determined to topple the thai government. >> we've got to get them out. we're playing ou